Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1347—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
  • G02F1/13471—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
  • G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
  • G02F1/141—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent using ferroelectric liquid crystals
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/13363—Birefringent elements, e.g. for optical compensation
  • G02F1/133638—Waveplates, i.e. plates with a retardation value of lambda/n
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F2203/00—Function characteristic
  • G02F2203/02—Function characteristic reflective

Definitions

• the present invention relates generally to compound retarders. More
• the present invention is directed to the use in display devices of achromatic
• Liquid crystal retarders are increasingly utilized within optical devices such as
• nematic devices and nematic pi-cells function as variable retarders, wherein application
• retardance at a design wavelength has higher retardance at shorter wavelengths
• the wavelength dependence of passive birefringent materials can be reduced by
• achromatic compound retarder is that a stack of waveplates with proper retardance and relative orientation can be selected to produce a structure which behaves as a pure
• the central retarder be a
• orientation of the external retarders relative to the central retarder is ⁇ /3.
• retarder can be halved, and one section mechanically rotated with respect to the other
• ferroelectric liquid crystals FLCs
• the cell gap is selected to yield a half-wave
• liquid crystal materials For instance, a visible FLC shutter device that equalizes on-
• This invention provides achromatic compound retarders, achromatic
• the external retarders are equal in retardance and oriented parallel to each
• the compound retarder is stable (achromatic) even though the composite retardance
• the central retarder may comprise a liquid crystal retarder, as described above.
• optic axis between two or more orientations.
• One of the orientations provides
• retarder is achromatic, even though the composite retardance is not. Furthermore, the
• the central retarder may also comprise a spatially switched planar-aligned
• retarder has at least two optic axis orientations states, with one of the orientations
• polarization switch of this invention comprising a linear polarizer and the compound
• variable birefringence retarders The first and second variable birefringence retarders
• the composite retardance of the pair is a half-wave retardance with orientation
• the active section comprises two liquid crystal retarders: a half-wave plate and a
• the passive section comprises two retarders: a quarter-
• the quarter-wave plates are positioned between the half-wave
• the composite retardance of the compound structure is 2( ⁇ /2- ⁇ ⁇ 2 + ⁇ 1 ).
• planar-aligned smectic liquid crystal cells of this invention have
• the smectic liquid is continuously or discretely electronically rotatable optic axes.
• crystal cells can utilize SmC * and SmA * liquid crystals, as well as distorted helix
• DHF dihydroxy-4-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-aminoethyl-N-N-(2-aminoethyl)-N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-aminoethyl-N-(2-aminoethyl)-2-a
• variable birefringence liquid crystal cells of this invention can include homogeneously
• the present invention may be achieved in whole or in part by an achromatic
• a first passive retarder unit having a predetermined retardance at a
• passive retarder unit having the same retardance as the first passive retarder unit at the
• the central retarder unit having a retardance ⁇ at the design
• the optic axis orientation varies between at least
• the present invention may also be achieved in whole or in part by a reflection
• achromatic compound retarder comprising: (1) a first passive retarder unit
• retarder unit having a retardance ⁇ /2 at the design wavelength, and having an optic
• optic axis orientation varies between at least a first orientation state
• the present invention may also be achieved in whole or in part by an
• achromatic compound retarder that exhibits a composite optic axis orientation and a
• composite retardance comprising: (1) a first passive retarder unit having a
• predetermined retardance at a design wavelength and having a predetermined optic
• first passive retarder unit at the design wavelength, and having substantially the same
• the central retarder unit having
• retardance is substantially achromatic at two orientation states of the central retarder
• the achromatic inverter works in combination with a liquid crystal display panel to
• reflective or transmissive display is capable of displaying an inverse image frame.
• display comprises one or more retarders having in-plane retardance and in-plane
• At least one of the retarders being an active retarder, and a ferroelectric
• the one or more retarders work in combination with the
• ferroelectric liquid crystal display to provide four states of brightness.
• a reflective display In accordance with another embodiment of the invention, a reflective display
• ferroelectric liquid crystal display In accordance with a further embodiment, a
• reflective display comprises a polarizing beam splitter, an actively controlled liquid
• a transmissive display comprises a first
• linear polarizer linear polarizer
• first actively controlled liquid crystal retarder and a ferroelectric
• liquid crystal display a second actively controlled liquid crystal retarded and a second
• the active retarder can be either a smectic or a nematic liquid crystal retarder.
• a reflective display In the accordance with another embodiment of the invention, a reflective display
• a linear polarizer comprises a linear polarizer, an actively controlled nematic liquid crystal retarder and a ferroelectric liquid crystal display.
• a ferroelectric liquid crystal display comprises a linear polarizer, an actively controlled nematic liquid crystal retarder and a ferroelectric liquid crystal display.
• reflective display comprises a polarizing beam splitter, an actively controlled nematic
• liquid crystal retarder and a ferroelectric liquid crystal display. In both embodiments,
• crystal display are both switchable between at least two orientations to provide in
• a passive retarder can be provided
• liquid crystal display Further, the actively controlled nematic liquid crystal retarder
• pi-cells can comprise one or more pi-cells. Where one or more pi-cells are employed as the
• a passive retarder can be located
• the display may display adjacent pi-cells. Further, in addition to the one or more pi-cells, the display may
• Figure 1 is a light shutter comprising a ferroelectric liquid crystal between
• Figure 2(a) illustrates a first embodiment of an achromatic compound retarder
• Figure 2(b) illustrates a second embodiment of an achromatic compound
• Figure 2(c) illustrates a third embodiment of an achromatic compound retarder
• Figure 3 (a) is a reflective achromatic compound retarder, in accordance with the
• Figure 3(b) illustrates a second embodiment of a reflective achromatic
• Figure 4 illustrates an achromatic shutter utilizing the achromatic compound
• Figures 5(a) and 5(b) are plots showing the calculated on- and off-state
• Figure 6 is a plot showing measured on-state transmission spectra of (a) a
• Figure 7 is the measured off-state transmission spectrum of a compound-retarder
• Figure 8 is a plot showing the calculated on-state transmission, as a function of
• Figure 9 is a plot showing the calculated off-state transmission, as function of
• Figure 10 is a plot showing the calculated contrast ratio, of a function of ⁇ , of
• Figure 11(a) is a plot showing the calculated on-state transmission spectra of an
• Figure 11 (b) is a plot showing the calculated off-state transmission spectra of an
• Figure 12(a) shows a multiple-pixel reflection-mode achromatic shutter having
• Figure 12(b) shows a multiple-pixel reflection-mode achromatic shutter having
• Figure 13 is multiple-pixel transmission-mode achromatic shutter, in accordance
• Figure 14 is a compound achromatic variable retarder comprising a pair of
• liquid crystal retarders and a pair of passive retarders in accordance with the present
• Figure 15(a) shows an arrangement of a general reflective display according to
• Figure 15(b) shows an unfolded revision of the reflective display of Figure 15(a);
• Figure 16 is a table that illustrates that the optimal modulation of a
• Figure 17 is a table illustrating that when a passive retarder is oriented at 7.5°
• the LCD panel rotates between 60° (ON), and 105° (OFF) ;
• Figure 18 is a table illustrating the performance for half-wave retarders centered
• Figure 19(a) illustrates a first embodiment of a reflection-mode achromatic FLC
• FIG. 19(b) illustrates a second embodiment of a reflection-mode achromatic
• Figure 20 is a table that shows the output of one pixel of the FLC display of Fig.
• Figure 21 is a plot of the optical transmission of the FLC display of Fig. 19(b)
• Figure 22 illustrates a transmission-mode achromatic FLC display that includes
• Figures 23(a) and 23(b) show optical inverters according to the invention
• Figure 23(c) shows an optical inverter implemented with a pair of nematic
• liquid crystal variable retarders with improved field of view (FOV) according to the
• Figure 24 shows an optical inverter according to the invention implemented
• Figure 25 illustrates preferred orientations of the passive retarder of the
• Figure 26 illustrates a preferred difference in angle between the optic axes of the
• Figure 27(a)-27(d) illustrate in diagrammatic form a preferred polarization
• Figure 31 shows another embodiment of a FLC display device with improved
• Figure 32 illustrates how off axis rays "see” a twisted liquid crystal director
• Figure 33 shows another embodiment of a FLC display device according to the
• Figure 33(a) illustrates preferred orientations of the various wave plates in the
• Figure 34 shows another embodiment of a FLC display device according to the
• Figure 34(a) illustrates preferred orientations of the various wave plates in the
• Figure 35 shows another embodiment of a FLC display device according to the
• Figure 35(a) illustrates preferred orientations of the various wave plates in the
• Figure 36 shows the basic structure of another reflective display according to
• Figures 37(a) - 37(b) show head-on spectra of four states of the embodiment of
• Figure 39 shows the basic structure of another reflective display according to
• Figures 40(a) - 40(b) illustrate a total of four states of intensity of the
• Figure 41 shows the basic structure of another reflective display according to
• Figure 42(a) - 42(b) illustrate a total of four states of intensity of the
• Figure 43 shows the basic structure of another reflective display according to
• Figures 44-47 show various display devices incorporating an achromatic inverter
• the elements in the devices of this invention are optically coupled in series.
• the orientation of a polarizer refers to the orientation of the transmitting axis
• orientation of a birefringent element refers to the orientation of the principal optic
• the retardance refers to the
• fixed retarder refers to a birefringent element wherein the orientation
• active retarder refers to
• Rotatable liquid crystal retarders of this invention have
• retarders have electronically variable retardance (birefringence) and fixed orientation.
• compound retarder is used for a group of two or more retarders which
• the composite retardance of a compound retarder is
• a spatially switched retarder refers to an active or passive retarder in which the
• orientation and/or the retardance varies as a function of position on the retarder.
• design wavelength and design frequency ( ⁇ 0 ) refer to the wavelength
• achromatic retarder refers to a retarder with
• achromatic orientation refers to an orientation of the optic axis with minimal first-
• FIG. 2a comprises planar-aligned smectic liquid crystal retarder 30 having an
• Retarder 30 orientations are herein termed the on-state and the off-state, respectively.
• the central retarder is an FLC, but it can be any material
• liquid crystals as well as distorted helix ferroelectric (DHF), antiferroelectric, and
• the retarder switches between at least two
• the rotatable retarder 30 is replaced by a spatially switched retarder 100.
• the spatially switched retarder 100 is prefereably a planar-aligned passive retarder with an optic axis
• the spatially switched retarder 100 has a
• retardance of the spatially switched retarder 100 at the design wavelength is preferably
• the spatially switched retarder 100 is termed the on-state and the off-state, respectively.
• the spatially switched retarder 100 is referred to the on-state and the off-state, respectively.
• 100 is divided into at least two portions 100a and 100b, with respective optic axis
• the spatially switched retarder 100 can be divided into additional
• the spatially switched retarder 100 can be any birefringent material. Suitable
• materials include crystalline materials, such as mica or quartz, stretched polymeric
• films such as mylar or polycarbonates, and polymer liquid crystal films.
• variable retarders 31 and 33 having fixed
• the retardances are synchronously switched which, as used herein, means that when one has zero retardance the other has half-wave
• Liquid crystal variable retarders 31 and 33 can include, but are not limited to,
• nematic cells and nematic ⁇ -cells are sometimes incapable of being electrically driven
• liquid crystal cell can be combined ("shimmed")
• the passive retarder to compensate for the residual retardance.
• variable retarders 31 and 33 optionally include passive retarders to compensate for non ⁇
• rotatable retarder can, in the manner of Fig. 2(c), be replaced by a pair of liquid crystal
• variable retarders The species of Fig. 2(a) is preferred over the species of Fig. 2(c) for
• the passive outer retarders can be any birefringent material. As discussed
• suitable materials include
• crystalline materials such as mica or quartz
• stretched polymeric films such as mylar
• dispersion of the passive outer retarders is approximately matched to the dispersion
• Mylar for example, has a similar dispersion to some FLCs.
• the achromatic compound retarder of this invention is designed to be
• the relative orientations of the retarders can be chosen to provide the desired
• retarder is achromatic, it teaches against changing the orientation of the central
• An aspect of the present invention is the
• composite retarder is not achromatic, the optic axis orientation is stable with respect
• a further aspect of this invention is the realization that in many devices the
• composite retardance does not affect device output in certain switching states and,
• retarder is oriented parallel to a polarizer, the polarized light is not modulated by the
• the optic axis In a preferred embodiment of the achromatic compound retarder, the optic axis
• orientation of the compound retarder is achromatic when the central retarder is
• Fig. 3(a) is the reflection-mode
• retardance of the liquid crystal quarter-wave retarder 32 is a half wave.
• Figure 3(b) illustrates a reflection mode embodiment of the retarder of Figure 2(b), and utilizes a spatially switched quarter-wave retarder 110, with retarder portions 110a and
• the reflector can transmit an optical signal for addressing the
• This invention further includes devices employing the achromatic compound
• the polarization switch of this invention comprises a linear
• the polarizer in combination with the achromatic compound retarder.
• the polarizer can be any suitable polarizer.
• compound retarder embodiments produce elliptically polarized light.
• polarization switch functions as a polarization receiver when light is incident directly
• the achromatic compound retarder is achromatic
• the polarized light does not " see " the achromatic compound retarder
• achromatic compound retarder is stable in the off-state, i.e., d ⁇ '/de is small.
• the orientation of the achromatic compound retarder is
• achromatic i.e., d ⁇ '/de is zero.
• the polarization switch 110 comprises polarizer 20,
• Outer retarders 40 and 42 are identical to outer retarders 40 and 42, and liquid crystal retarder 30.
• Outer retarders 40 and 42 are identical to outer retarders 40 and 42, and liquid crystal retarder 30.
• the liquid crystal retarder 30 is a
• achromatic compound half-wave retarder has an achromatic orientation for all values
• the polarization switch 110 can be used in combination with any polarization
• the polarizers 20 and 22 are
• One advantage is that the shutter of the present invention is
• the achromatic shutter demonstrates the wavelength stability of the devices of this
• the Jones matrix for the compound half-wave retarder is the product of
• W ⁇ ( ⁇ /4) W( ⁇ + ⁇ , ⁇ /12)W( ⁇ + ⁇ ,5 ⁇ /12)W( ⁇ + ⁇ , ⁇ /12) (6)
• W c (0) W ⁇ + ⁇ , ⁇ /12)W( ⁇ + ⁇ ,2 ⁇ /3) ( ⁇ + ⁇ , ⁇ /12) (7)
• retarder is assumed identical in material and retardance, with half-wave retardation at
• This wavelength is preferably selected to provide optimum peak transmission and contrast over the desired operating wavelength band.
• the dispersion is modeled using a simple equation for birefringence dispersion that is
• the Jones vector for the transmitted field amplitude is
• the polarizers are taken to be ideal
• smectic liquid crystal compound retarder is by rotating the orientation of the
• the output is ideal to this degree
• FIG. 5(a) shows a transmisstion spectrum
• the shutter has a 90% transmission bandwidth of 335
• Fig. 5(b) shows the transmission spectrum for a conventional
• the conventional shutter has a 90%
• the first-order orientation stability requirement of the optic axis allows
• outer retarders have dispersion identical to the FLC, a worst-case contrast ratio of
• substrates were spin coated with nylon 6/6 and were rubbed unidirectionally after
• the substrates were gapped by applying a uniform pressure with
• a conventional shutter such as the one shown in Fig. 1, was formed by placing
• HN22 polarizers were used due to their high contrast throughout the visible
• the structure was probed by illuminating it with a 400 W Xenon
• the achromatic shutter was assembled using the same FLC device positioned
• contrast ratio is anticipated for the achromatic compound retarder due to increased off-
• the polycarbonate films were oriented at 15° with respect to the input
• achromatic polarization switches and shutters of this invention can also be used.
• a polarization switch can be fabricated using a linear polarizer and an
• achromatic compound quarter-wave retarder In one embodiment, the orientation
• the achromatic shutter of this invention can be utilized in applications such as
• the achromatic shutter can be used in a multiple-
• the FLC cell is formed with substrates 90 and
• the compound retarder is formed by the FLC in combination with
• passive half-wave retarder 40 oriented at ⁇ /12.
• the shutter array uses linear polarizer 20 oriented at 0°. Since, in Fig. 12(a) the shutter array uses linear polarizer 20 oriented at 0°. Since, in
• polarizer 20 is both the input and output polarizer, this is a parallel
• the array is illuminated by ambient light 100 and the viewer
• Fig. 12(b) the array uses polarizing beam splitter 25 to
• White light 101 illuminates the array and
• modulated gray light is output to the viewer.
• a transmission-mode array is illustrated in Fig. 13.
• FLC has a half-wave retardance. Voltages are applied using transparent electrode 95
• the compound retarder is formed by the FLC
• the shutter is formed by
• backlight assembly 103 which can be collimated by lens 104.
• the display is viewed
• retarder orientations can be tolerated. Specific examples include polarization
• the birefringent element is oriented at ⁇ /4 with respect to a
• the retarder units can include a rotatable liquid crystal retarder.
• interference filters can be replaced with the achromatic compound retarders of the
• circular polarization handedness switch and the linear polarization switch comprise
• the color filters use the
• polarization switch in combination with a color polarizer, such as a cholesteric circular
• the achromatic compound retarder can also be used to improve other color
• they further comprise pleochroic polarizers, and in other embodiments
• they further comprise a second linear polarizer and a passive birefringent element.
• the simple liquid crystal rotatable retarder of the Handschy et al. invention can be any liquid crystal rotatable retarder.
• the color filters of this invention can be temporally multiplexed, wherein the
• output color is switched on a timescale which is rapid compared to a slow response
• retarder of this invention is that the single retarder must be rotatable between two or
• the achromatic compound retarder is especially
• orientation of the retarder is, in one of its switching states, parallel to the
• the achromaticity of the compound retarder is particularly
• achromatic compound retarder of this invention can also be used in optical
• retarders have first and second fixed orientations, and have retardances switchable
• this invention provides an achromatic compound retarder
• An active section comprises
• smectic liquid crystal half-wave retarder 60 oriented at ⁇ 2 , and smectic liquid crystal
• quarter-wave retarder 65 oriented at ⁇ 2 + ⁇ /3. Angle ⁇ 2 of retarders 60 and 65 is
• a passive section comprises passive
• quarter-wave retarder 75 oriented at o + ⁇ /3, and passive half-wave retarder 70,
• retardance of the compound structure is 2( ⁇ /2- ⁇ 2 + ⁇ 1 ).
• achromatic compound retarders of the present invention can be used to solve the achromatic compound retarders of the present invention.
• FLCs are generally binary electro-
• optic devices that are operated in a one-bit mode, where (relative to the input
• FLCs respond to the polarity of applied voltage. That is, the optic axis
• Figure 15(a) shows an arrangement of a general reflective display according to
• the reflective display of Figure 15(a) comprises a stack of
• orientations ⁇ ,- ⁇ N at least one of which may be active, sandwiched between a
• PBS polarizing beam splitter
• LCD panel FLC display panel
• the LCD panel 370 may comprise,
• an FLC retarder 360 sandwiched between a transparent electrode (not limited to, an FLC retarder 360 sandwiched between a transparent electrode (not shown).
• N 0: A standard FLC panel with no inverter, previously discussed in
• N l: A standard FLC display panel with the addition of a passive
• N l: A standard FLC display panel with the addition of an active
• retarder This is the simplest structure that can implement an inverter according to
• N ⁇ 2 A standard FLC display panel with one active and one or more
• This structure can have improved contrast
• Figure 15(a) is a reflective (two pass) device.
• the LCD panel 370 is preferably a chiral smectic liquid crystal (CSLC) spatial
• classes of CSLCs that can be used include SMA*, SMC' 1 ' including ferroelectric displays currently being commercialized by
• switch can either be a nematic liquid crystal (NLC) or smectic (FLC) device.
• NLC nematic liquid crystal
• FLC smectic
• the single-pixel switch can be an electronically controlled
• EDB birefringence
• nematic cell or another LC device that allows switching between a non-zero retardance
• a NLC behaves as a zero-twist retarder in the low-voltage state
• the retarder is effectively not seen by the input light (i.e., vanishes). Note that
• the second cell improves switching speed, but the combination can be
• the scheme in general modulates between structures with
• the single-pixel FLC device switch is also taken to behave as an in-plane switch
• the tilt angle and retardance can in principle be selected to
• the FLC device switch is directly adjacent to the polarizer oriented along an
• FLC solutions can either have a fixed N
• NLC to the low state produces the additional states.
• the NLC orientation is
• the optic axis The optic axis.
• the chrominance of the on-state is fixed by the OFF-state requirements.
• the on state is less chromatic than an LCD panel alone.
• the M 3
• structure is a compound retarder with compound optic axis switchable by the NLC
• passive retarder can be placed either between the PBS and the NLC, or between the
• orientations can be selected for an OFF-state corresponding to an eigenstate of the
• the compound retarder is an achromatic half-wave plate, which requires
• the passive retarder is also a half-wave plate.
• the OFF-state is obtained as an
• the passive retarder is oriented at 15° and the
• NLC rotates between orientations of 75° and 120°. What remains is to select the
• the higher order structure can also be considered a half-wave compound
• the NLC must be used to determine the
• the NLC must generate an OFF-state, which is done by orienting an
• the contrast ratio degrades for any ⁇ either greater or less than 90°. Therefore, one
• This on-state is somewhat less chromatic than a zero-order half-
• the FLC switch rotates between 60° (ON), and 105° (OFF).
• ⁇ 2 Select to control chrominance (typically 5°-15°)
• tilt angle of the FLC retarder in the LCD panel is less than 22.5°, for
• Figures 19(a) and 19(b) show specific configurations, of a reflective achromatic
• the reflective display 500 of Fig. 19(a) comprises
• a linear polarizer 510 an actively controlled liquid crystal (FLC) retarder 520 (switch),
• FLC actively controlled liquid crystal
• an FLC retarder 560 for applying a voltage across the FLC retarder 520; an FLC retarder 560, preferably a
• electrodes 580 and FLC retarder 560 collectively make up an LCD panel 600.
• the linear polarizer 510 is oriented at 0°.
• the embodiment is a parallel polarizer embodiment.
• the display 500 is illuminated by
• the LCD panel 600 is configured to control the ambient light 100 and the viewer is represented by an eye 300.
• the LCD panel 600 is configured to control the ambient light 100 and the viewer is represented by an eye 300.
• a polarizing beamsplitter 511 which is used as both an input polarizer and an
• the polarizing beamsplitter 511 is illuminated
• white light 101 reflects light having a first polarization and transmits light having
• FIG. 19(b) is a crossed polarizer embodiment.
• the achromatic display is formed by the LCD panel 600 in combination with the actively controlled FLC retarder 520 (switch), which functions
• the FLC retarder 520 has an orientation that is electronically switchable
• the FLC retarder 560 has an orientation
• orientation of sections or "pixels" of the FLC retarder 560 can be independently
• the LCD display 600 polarization modulates the input light 100
• wavelength are preferably chosen so that the retardance provided by the FLC retarder

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• 1999
  • 1999-12-17 AU AU24810/00A patent/AU2481000A/en not_active Abandoned
  • 1999-12-17 JP JP2000588645A patent/JP5247955B2/ja not_active Expired - Fee Related
  • 1999-12-17 WO PCT/US1999/029985 patent/WO2000036462A1/en active Application Filing
  • 1999-12-17 EP EP99968132A patent/EP1151346B1/de not_active Expired - Lifetime

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